Vehicle suspension assembly

ABSTRACT

Suspension assembly consisting of a bearing structure capable of being fixed to the chassis of a vehicle. The structure holds the composite leaf spring in position to the ends of which the wheel supports are fixed. The supports are connected to the structure by the wishbones and the shock absorbers. Different positions of the composite leaf spring, wishbones and shock absorbers are described.

The invention relates to a vehicle suspension assembly with a transversecomposite leaf spring comprising a composite leaf spring having adeveloping profile of increasing thickness and of decreasing widthtowards its ends, a wheel support connected on the one hand to thespring and on the other hand to the chassis by a wishbone or connectingarm, a shock absorber unit being provided between the wheel support andthe body for damping the amplitudes.

An automobile suspension with a composite leaf spring is known, forexample, from French Pat. No. 2,516,455, corresponding to U.S. Pat. No.4,557,500. This spring is placed transversely under the chassis of avehicle to which it is held in position by connecting components,symmetrically in relation to the axis of the vehicle. As a result of theparticular features of the spring, obtained not only due to its shapebut also due to its method of manufacture, it has been possible toabolish the coil springs of the shock-absorbing device ensuring thevertical return of the vehicle to its static position and to lighten oreliminate the wishbones connecting the wheel supports to the chassis,which transmit the braking forces and ensure the geometric positioningof the wheel axis. The shock-absorbing device is thus reduced to adamping strut only, ensuring the vertical guidance of the wheel axis andthe damping of amplitude.

The attitude adopted by the composite springs in the working position isappreciably different from that which they adopt when they are under nostress whatsoever. The springs are more or less curved sharply in theirplane of longitudinal symmetry and, when fitting them to a front or rearaxle of a car, they need to be set up in order to be able to fix them tothe connecting devices on the chassis and to the wheel supports. Toolingenabling a preload to be applied to the spring for its setting up isknown and is used for fitting the springs to and removing them from thesuspension components already fitted on the vehicle.

The location of the axles and the preload which must be applied to thecoil spring or to the leaf spring do not allow an improvement ofassembly times on production lines or during repair or maintenance work.

The subject of the present invention is a suspension assembly comprisinga bearing structure, capable of being fixed to the chassis which holdsthe leaf spring in position to the ends of which are fixed the wheelsupports, the said supports being themselves connected to the saidstructure by wishbones or connecting arm and shock absorbers.

The bearing structure consists of two mountings, connected at leastprovisionally by a beam, in which the leaf spring, wishbones and shockabsorbers are held in position.

The explanations and figures given hereinafter as examples enable anunderstanding of how the invention may be embodied.

FIG. 1 is a front view of a first exemplary embodiment of a suspensionaccording to the invention.

FIG. 2 is a view form below of figure 1 in which the wishbone and theshock absorber have been removed on the right-hand side of the drawingto show the fixing of the spring.

FIG. 3 is a front view of a second exemplary embodiment of a suspensionaccording to the invention.

FIGS. 4, 4A; 5, 5A; 6, 6A show three examples of the shock absorberlayout in relation to the spring and to the wishbones or connecting arm.

FIGS. 1 and 2 show an automobile suspension with a composite leaf spring1, viewed respectively from the front and from underneath. As is known,this spring has a central part 2, of relatively thin and widerectangular section united at its ends to parts 3, 4 having a developingprofile of increasing thickness and decreasing width. This spring isheld in position in connecting devices 5, 6 provided in the mountings 7,8 constituting the bearing structure fixed to the chassis 9 of thevehicle.

According to the embodiment shown, the mountings 7, 8 are in the form ofa "U" section with triangular sides. These mountings are fixed to or arean integral part of a frame in the shape of a beam 10 ensuring theirpositioning and bearing the preload stresses applied to the spring.

According to an embodiment not shown, the frame is made up of tworemovable beams fastened to the sides of the mountings so as to be ableto be withdrawn after the said mountings have been fixed to the chassis.

The mountings are also fitted with bearings in which the pins 11, 12,around which the bottom of the wishbones or connecting arms 13, 14turns, are inserted.

The wheel supports 15, 16 are held in position at the ends of the springblade and at the apex of the wishbones. These supports each have twoyokes 17, 18 and 19, 20 in which bearings of parallel pins are provided.The bearings of one of the yokes 17, 19 accept pins 21, 22 whichinteract with the brackets 23, 24 provided at the ends of the leafspring, those of the other yoke 18, 20 accept a pin 25, 26 interactingwith the apex of the wishbones or connecting arms 13, 14 and possiblywith the shock absorber rod 27, 28 the body of which is hinged on themeans of holding in position 29, 30 formed by a yoke provided in themountings 7, 8.

The exemplary embodiment in FIG. 1 is intended more particularly for therear suspension of a vehicle and in consequence has stub axles on ahorizontal axis. Furthermore, the leaf spring is located above thewishbones or connecting arms and is proteced from projections due to itsdistance from the road surface. Also as shown in FIG. 1, parts 3, 4 andconnecting arms 13, 14 form parallelograms with mountings 7, 8 and wheelsupports 15, 16.

In the case of mountings integral with a "U" section beam, the sides ofthe "U" enable part of the blade at least to be boxed in. Possibly astop 31 is provided on the center part at the back of the beam 10.

The preceding embodiment, with a leaf spring at the top, may be used fora rear axle and is particularly interesting in the case where it isdesired to have sufficient space available for locating a spare wheel,for example.

In the exemplary embodiment shown in FIG. 3, similar components to thosedescribed in the preceding example bear the same reference numbers. Thedifferences concern mainly the relative positions of the wishbones andthe leaf spring. The spring is now in the bottom position and thedevices connecting the blade to the mountings are at the bottom end ofthe mountings at 32, 33, the fixings for the bottoms of the wishbones13, 14 being moved up to 34, 35 approximately in the position of theconnecting devices for the spring in the proceding example.

Also shown on this example are wheel supports in the form of verticalstub axles such as those which are found on certain front axles forutility vehicles and trucks, for example.

The shock absorbers 27, 28 are located, in this exemplary embodiment,approximately between the ends of the brackets 23, 24 for the spring 1and the pin 34, 35 around which the bottoms of the wishbones 13, 14pivot.

This same layout of the shock absorbers may be adopted in the examplefor FIGS. 1 and 2 and inversely the layout of the shock absorbersaccording to the example in FIG. 3 may be adopted for FIGS. 1 and 2.

The shock absorbers are in the vertical symmetrical plane of thesuspension assembly as shown in FIGS. 4, 4A. They are thus held inposition at one of their ends by one of the pins holding the wishbone13, 14 in position and at the other end by a pin held in position in ayoke fixed either on the mountings 7, 8 or held in position by the pinfor the brackets 23, 24 of the spring 1.

According to the example of the layout shown in FIGS. 5, 5A, and showingonly one side of the suspension, the other side being identical, anextension 36 (or 37 shown in dotted lines) of the bottom part of thewheel support 15 (or of the mounting 7) having a pin 38 (or 39), isprovided, in which one end of the shock absorber 27 is fitted, the otherend being held in position in a yoke 29 provided on the mounting 7 (oron the pin 21 of the yoke 17 for the wheel support 15).

The example of FIGS. 6, 6A shows an embodiment in which the shockabsorbers 27 are arranged in a plane parallel to the symmetrical planeof the suspension assembly and external to the said assembly.

This layout may be used in the example in FIGS. 5, 5A with the bottomextension 36 or 37 of the wheel support or of the mounting.

One end of the shock absorber 27 is fitted on an external extension ofthe pin 25 whereas the other end of the shock absorber pivots around apin 40 forming a means of retention bearing against one of the sides ofthe mounting 7.

The different examples described earlier enable the suspension to beadapted to the different problems which may arise depending on the typesof vehicle to which it is desired to fit it.

The top of bottom position of the leaf spring may be chosen depending onspace requirements for, for example, a spare wheel (top spring) or anengine sump (bottom spring). It is just the same for the position of theshock absorbers in the plane parallel to the symmetrical plane of thesuspension.

We claim:
 1. A vehicle suspension assembly including a transverse leafspring, two symmetrically spaced mountings, two wheel supports and tworigid connecting arms, said leaf spring contructed and arranged forconnection to a vehicle frame with said two symmetrically spacedmountings and being pivoted at its opposite ends to said two wheelsupports respectively, and said two rigid connecting arms extendingparallely to opposed outer portions of said leaf spring and operativelypivoted to the vehicle frame and wheel supports respectively, whereinsaid leaf spring is made of unidirectional composite material ofconstant cross-sectional area, the thickness and the width of each outerportion of which increases and decreases respectively from each of saidmountings towards the respective end of said leaf spring, whereby saidend portion is rigid and constitutes a deformable parallelogram togetherwith the corresponding connecting arm and wheel support, and wherein ashock absorber is operatively mounted substantially diagonally betweenopposite ends of said connecting arm and outer portion of said leafspring of said deformable parallelogram.
 2. A vehicle suspensionaccording to claim 1 wherein said outer portion of said leaf spring andsaid connecting arm have substantially the same operative length betweenthe wheel support and the vehicle frame.
 3. A vehicle suspensionaccording to claim 2 wherein said connecting arm includes a pair ofconnecting rods encompassing said shock absorber.
 4. A vehiclesuspension according to claim 3 wherein said shock absorber isoperatively mounted between the mounting of said leaf spring and thediagonally opposite end of said rods.
 5. A vehicle suspension accordingto claim 3 wherein said shock absorber is respectively mounted betweenthe end of said leaf spring and the diagonally opposite end of saidrods.
 6. A vehicle suspension according to claim 3 wherein the outer endof said shock absorber is pivoted on an extension of said wheel support.7. A vehicle suspension according to claim 3 wherein the mountings ofsaid leaf spring and the pivoted arm end of said connecting rods andshock absorber are carried by a rigid structure to constitute anintegral suspension assembly to be secured under the vehicle frame.